Lh24 cut out/ lean

Car has B230ft, LH24 swap in it from a 1991 940, using 1991 240 harness

I'm getting ready to go to Portland this AM, jump on the freeway, and the car starts sputtering and the WB gauge goes full lean. I though "hmm, intank fuel pump?" So I quickly swap it with the one from my running wagon (740 turbo) and still the same.

Looking for ideas on what would cut fuel at just slight throttle. Floor the car and it flat rips along. But light throttle cruising is full lean and stumbling all over itself.

I had 600 trouble free miles on it until now.

Loose connection? Check the amm and tps, 600 bouncy miles may have jiggled something that comes back when the engine shakes

Follow up, what are standard cruising afr? Freeway, 10 in vacuum, 2700 rpm

No load/boost should stay around 14s.

Have you recently messed with anything?
Light throttle falling flat seems like a vacuum leak. Could be so small that under light throttle it fails.

Sounds like open loop is fine and the problem is while in closed loop. Verify connections to the key part while in closed loop, the O2 sensor.

After a big fat scramble, the MAF seems to be the cause of the lean condition, swapped it with a remann unit and the car ran better, but now it's the opposite spectrum. Car runs really rich at idle, and on the freeway the a/f gauge dances around between 13.8-15.1, just a constant bounce. Where should I go from here?

Here's a vid at idle, I'll try to grab a freeway vid shortly.

https://youtu.be/1b-9SvunDIE